Add a limit and last_seen argument to interface and mock for listing groups
Add limit and last_seen (offset) to cass model list scaling states
Shorten diff a bit
lint fix
Added cloudcafe test to ensure that list scaling group lists groups in ascending order by group ID
Change 'last_seen' to 'marker' so it matches other openstack APIs
Change cql to cql_parts to make it clear that the CQL is being assembled from bits, thanks @manishtomar
Merge pull request #385 from rackerlabs/paginate-groups

Paginate groups